1. Field of the Invention
The present invention relates generally to a material having an internal cooling passage and a method for cooling a material having an internal cooling passage. More particularly, the invention relates to a material having an internal cooling passage with a wall surface which includes cooling ribs.
2. Description of the Related Art
A material provided with an internal cooling passage has been described in Japanese Patent No. 3006174 (U.S. patent application Ser. No. 08/255,882). In this description, cooling ribs inclined relative to the flowing direction of a cooling medium are provided to cause the cooling medium to flow along the wall surface of the cooling passage to promote the occurrence of a turbulent flow and a flow from the center of a wall surface to a side edge thereof.
The cooling passage with the ribs disclosed by Japanese Patent No. 3006174 has a large recirculation area, which does not relatively contribute to heat transmission, at a position downstream of a rib in the flow direction of the cooling medium. The recirculation area lowers the thermal transfer performance of the entire cooling passage.